Game Mechanics for armor

Hey, I'm just wondering if there's a general guide for game mechanics as far as armor is concerned.

I mean, obviously the more armor you have the less likely it is that you take hits, but since it doesn't decrease damage it leads to me getting SHAT on by bone spear any time someone wants to PvP. Besides general guides to armor, does anyone know of general guides to magic damage reduction? (Though don't get hit is a decent enough strategy at times)

Imo the only char that can withstand magical damage (bonemancer and hammerdin) for a few hits is an ES sorc, since the damage is derived from the mana pool instead of the health pool.

But even a supreme ES sorc can absorb that much damage.

Don't even try to consider magicdamagereduction gear, even if you can get 200 magicdamagereduction (which is impossible) it's of no use when you face 3k or more pvp damage. It'll slaughter anyone in 2-3 hits, regarless if they have 0 or 200 magicdamagereduction.

Magic damage is special in that there are very few ways to reduce. Safety shields are the only item with magic damage reduced by x%. Physical damage is special in that it's the only one with a cap. Poison damage is special in that it works over time, can't be absorbed unlike the other damages on the character screen, and that it can be resisted in two ways, although a poison resist shrine is the only way to be immune to it.